In general, motorcycles are equipped with an ABS (antilock brake system) unit to prevent wheel locking at the time of sudden braking. The ABS unit receives detection signals from wheel speed sensors for detecting wheel speeds and an inertial sensor for detecting acceleration and an angular velocity and other signals, and controls brake pressures for front and rear wheels on the basis of the detection signals (refer to JP-A-2009-292350, for example). Since inertial sensors of this type should satisfy strict vibration conditions, a vibration preventive measure is taken in which a bracket of the inertial sensor is supported by a vehicle body frame in a floated manner via vibration absorbing members. Vibration coming from the vehicle body frame is absorbed by the vibration absorbing members, whereby vibration to travel to the inertial sensor is suppressed.